Electrical switching apparatus



March 17, 1953 s. R. SMITH ET AL 2,632,055

ELECTRICAL SWITCHING APPARATUS Filed 0013. 19, 1949 2 SHEETS-SHEET 1 r A QLESQS'QTEEQ Q T L X )dbd si t: i n gYigLmg & i

Z Ia m f PHI March 17, 1953 s. R. SMITH ET AL 2,632,065

ELECTRICAL SWITCHING APPARATUS Filed Oct. 19, 1949 2 SI-IEETSSI-1EET 2 Patented Mar. 17, 1953 ELECTRICAL SWITCHING APPARATUS Sidney Reynell Smith and Harold William Barrett, Liverpool, England, assignors to Automatic Telephone & Electric Company, Limited, Liverpool, England, a British company Application October 19, 1949, Serial No. 122,248 In Great Britain November 2, 1948 1 Claim. 1

The present invention relates to electrical switching apparatus of the type employing a plurality of contacted leaf springs secured towards one end in a pile and suitably interleaved by insulators to make a so-called springset for actuation by lever, cam, push rod or the like and having particular application to electromagnetic relays, selectors and like equipment in automatic telephone and other electrical signalling systems.

Such springsets fall broadly into two classes. The first of these classes, of which those embodied in relays of the British Post Oifice 3000 and 600 types are examples, employ lifting pins and/or studs of metal and/or insulating material which serve mechanically to interconnect the so-called lever or moving springs in each of the contact units forming the springset so as to enable the movement of the armature to be communicated to them whilst maintaining them elec- .trically isolated. Relays of the foregoing type are now standardized by the British Post Office. In the 3800 type relay the core and the associated winding or windings form a complete subassembly which may be withdrawn from the relay by re- :moving a single unit. The windings are terminated on tags fixed to the Bakelite rear coil cheek, while the core is of L-shape and has a machined knife-edge on its front extremity. The construction provides a close magnetic joint between the yok and the core which are clamped together by the above-referred-to nut. The armature is of like construction and rides on the knife-edge. Lateral displacement is avoided by means of a spring-loaded fixing screw. The outstanding feature of the 3000 type relay is the provision of a buffer block which serves as a positioning piece for the contact springs. The front portion of the block is formed into a series of steps which engage with projecting lugs on the side of the contact springs. The contact units are arranged in two piles, one on each side of the buffer block, and the loads of the two piles are arranged to be as equal as possible. The movable springs of the contact units are operated by lifting pins with which the armature engages during its movement when the coil is energized.

The 600 type relay is very similar in construction. However, it is designed for use in circumstances where space and cost are important, and when critical performance is not required. The main difference might be regarded as resting in a simplification in the knife-edge mounting of the armature, as well as certain limitations in the number of contact units which can be provided. This class of springset suffers from the disadvantage of involving the manufacture of the various kinds of lifting pins and/ or studs and the comparatively laborious and time-consuming operation of securing said lifting pins and/o1 studs to the lever springs. The second class of springset is known as the comb-actuated type and employs a comb-like member of stiff electricallyinsulating material passing into slots in the contacted springs and having teeth or notches which co-operate with the lever springs. In one form, this class of springset, even though it may have two or more contact units, has hitherto involved the inclusion of a number of members, in addition to the electrically-conducting springs, to serve as locating means whereby the teeth are maintained in a suitable Working position relative to the lever springs. Another form of combactuated springset, although not involving any additional member, has required the partial closure of the slots in the lever springs in order to interlock the comb and the lever springs and this has been accomplished after the comb has been placed in position by performing a bending operation on a tongue forming part of each of said springs.

, The object of the present invention is to provide a simple and improved comb-actuated springset which has a long and useful life and is quick and easy to assemble.

According to one feature of the invention in a comb-actuated springset comprising one or more contact units each including a contacted lever spring and at least one associated substantially stationary contacted spring, the springset being operable by an external force applied to a comb member of insulating material arranged toengage with the lever spring or springs and being restored due to the resilience of the lever springs, the comb member is retained in its workmg position by interlocking means provided between the comb member and the outer lever springs of the springset where the latter comprises more than one contact unit or where the springset comprises a single contact unit only between the comb member and the lever spring of the contact unit and an additional spring, said comb member being so shaped as to be capable of insertion into or removal from the springset by flexing one or more of the springs in a direction which is opposite to the operating movement of the lever spring or springs.

According to another feature of the invention, in a comb-actuated springset comprising one or more contact units each including a contacted lever spring and at least one associated substantially stationary contacted spring, the springset being operable by an external force applied to a comb member of insulating material arranged to engage with the lever spring or springs and being restored due to the resilience of the lever springs, the comb member is provided with a head and foot so dimensioned with respect to slots provided in the outer lever springs where more than one contact unit is employed or where a single contact unit is employed provided in the lever spring and an additional lever spring that the comb member is maintained in its working position, the insertion and removal of the, comb member from the springset being effected by flexing one or more of the springs in a direction which is opposite to the operating movement of the lever springs whereby due to the position and the dimensions of slots in the remaining springs with respect to the slots in said outer lever springs. the comb. member is capable of being threaded through the slots soas to take up its working position.

Accordin to a further feature of the invention, in a comb-actuated. springset comprising one or more contact units each including a contacted lever spring and at least one associated substantially stationary contacted spring, the springset being operable. by an external force applied to a comb member of insulating material arrangedto engagewith the lever springer springs and being restored due to the resilience of the lever springs, the comb member passes through slots in the springs and is providedwith a head which when the comb member is in the Working position is prevented by its size from passing through the slot in an outer lever spring, the insertion and removal of the comb member being effected by flexing one or more of the springsin a direction which is opposite to the operating movement of the lever springs and threading the. comb member through the slots in the springs wherebydue to the shape of the head of the comb member and the length of the slots in the springsother than the outer lever spring, the head" of the comb member, during the threading operation is. presented to the slot in the outer lever spnng'm' such a direction that the head is able to pass 'through s gmen The invention will be better understood from the. following description of methods, of; carryingit into effect anathema be read in conjunce tion with the accompanying. drawings wherei n Figs. 1 to 3 show, in skeleton form, an electromagnetic relay with a springset having a co rnpara tively large numberbf contact units while Figs. 4 and 5 show, also in skeletonform, a relay of the same type but having a springset comprising two contact units only. Of Rigs. 1 to3, Fig. 1 represents a side view of a, relay, Fig. 2 is, a sectional view in the direction A- -A of Fig. 1, and Fig. 3 is 'a part plan View. Figs. 4 and 5. represent side and sectional views respectively of a relay, the latter being the direction B,-B of Fig. 4.

Referring first to the embodiment shown in s.- 1 to 3 it ll s i adv ntaaet! on ider that the relay shown is broadly along the lines of the British Post" Office type 3909 relay. In the present example the springset comprises four contact units being, from bottom to top, a make, a changeover or 'break-make, another, make and finally a break. The contacted springs which are of the well-known twin contacted and bifure cated type are individually referenced 1.0;to18.

upwardly, and are clamped, suitably spaced by insulators such as l9, between the metal plates 20 and 2|. Before the springset is assembled to the heelpiece 22, the operating member 23, which will henceforth be termed a comb, and is of inflexible electrically-insulating and stable material is threaded into position within the various slots such as 24 in the springs. In order that the slots may be more clearly defined in Fig. 1 the portions of the springs about them are shown broken away near the comb. As regards the slots, these are axial with the springs and, as can be seen from Fig. 3, are slightly wider than the comb which is of uniform thickness. It may be convenient to refer to right-hand and lefthand limits of the slots as the front and back edges respectively. Now the front edges of the slots in all the so-called lever springs, namely ill, I3, I5 and iii are displaced towards the left with respect to the others in order to provide coperating surfaces for the comb teeth 25, 26, 2'! and 28 respectively, thefront edges of theslots in springs l0 and 38 being slightly moreto the left than the others mentioned. The back edges of the slots in the lower and upper. lever.

springs l0 and it are considerably more towards the right than all back edges of the slots in the intervening springs. It follows therefore that the leftward movement of; the comb is limited by the engagement of projections 2% and 39 on the back of thecornb, with the back edges of the slots in springs- Ill and I3;

respectively, while the rightward movement of the comb is limited by engagement of the forward edges of the same. slots with the back of the depressions above teeth 25 and 28. Furthermore when the comb is in position and the springset is not as yet mounted on the heelpiece, the

downward movement of the comb with ordinary handling of the springset is limited by the tooth 3| which would engage with the upper surfaceof spring l8. It will therefore be seen that oncethe Qm is nrq itiona arel pe p ble atera movement-and a slight axial movement may be obtained but there is no danger of the comb be coming disengaged.

Considering therelay from the aspect of arias- -v senibling operation the method of threading the comb into position in the yet unmounted spring ,v set [W111 first be described With the foot of the, comb lying towards the right the tooth 31 is, placed in the slot in spring It then thefoot of, the comb is moved to the left until theprojece tion 30 is above spring Ml. lhe foot of the comb is moved again towards the right so. that the, comb is substantially vertical, and then the. comb is moved bodily leftwards until the projection 30 meets the back edgeof the slot in spring II. By gently pushing the comb upwardly, it-

passes freely through the slots in the springs untilthe upper end forming projection 30 andtooth 3| meets spring IB, It will be noted thatthe horizontal dimension of said endis greater thanthelength of the slot in spring i8 so that the comb is prevented from passing directly through that slot. However, by flexing all the. springs downwardly, gradually reduced di1nen.-. sions of the comb end are presentedto the slot. in spring is so that when thesprings are adee, quately deflected the end maybe passed through.

by moving the comb upwardly and to the right; Finally the contacted springs are relaxed and they and the comb assume positions somewhat. as,

shown, tooth 3i preventing the comb from falling too far. Should it berequiredto removethe.

comb at any time the reverse sequence of operations will be observed.

Having fitted the comb to the springset the latter is secured to the relay heelpiece 22 upon which the buffer block 32, shown only in Fig. 2 for simplicity, is also mounted. Following known practice the so-called'fixed springs I I, l2, l4, l6 and I! are provided with extensions which cooperate with shoulders in the. buffer block. Of the said springs, 4 and I6 being included in make contact units or the make portion of a changeover unit are tensioned downwardly, while springs I2 and I1, being included in a break unit or the break portion of a changeover unit are tensioned upwardly. The last mentioned springs are however lifted clear of the block shoulders by the downward pressure of the associated lever springs. When the relay coil (not shown) has been secured to the heelpiece in known manner, the V-shaped armature 33, carrying the phosphor bronze backstop stud 34, is mounted on the knife-edge 35 of the heelpiece and this operation causes the comb to be raised slightly so that teeth 25 to 28 touch their appropriate lever springs.

Now when the relay coil is energized the armature is urged over a predetermined angle in the direction of the arrow 0. Consequently the comb is moved upwardly against the tension of the lever spring to operate the springset and in so operating those lever springs, namely l0, l3 and 5, associated with make contact units engage respectively through the intermediary of the contacts, with the relevant so-called fixed springs l4 and I6 which are lifted slightly clear of the buffer block shoulders. Subsequently, when the electromagnet is de-energized, the armature is urged back to the position shown by the pressure of the lever springs extending through the comb.

In order to increase the efliciency and useful life of the relay, friction is reduced to a minimum and accordingly the top faces of teeth 25, 26, 21 and 28 are sloped downwardly in the direction of the body of the comb to ensure that they shall each co-operate with a smooth portion of a spring and avoid engagement with the edge of a slot which may be sharp or rough. Another important point concerning the limitation of friction relates to the foot of the comb upon which the pressure of the springset is concentrated. In this respect the very slight forward and backward motion of said foot, permitted by the clearance in the slot in spring I and taking place during the arcuate motion of the relay armature 33, ensures that the foot rocks on its substantially arcuate surface instead of sliding on the surface of the armature.

Reference will now be made to Figs. 4 and which are representative of a relay of the same type as that already described but employing a contacted springset comprising one changeover, or break-make, and one break contact unit. Here the changeover unit comprises springs 40, 4| and 42 while the break comprises springs 43 and 44. The springs together with insulators are secured in pile as before and it will be noted that the slots in the lever springs, namely springs 4| and 44, are shorter and lie well within the limits of the slots in all the other springs. The comb 45 is manipulated into position, before the springset is mounted on the heelpiece, in a similar manner to that described in the previous example, to enable the sloping teeth 46 and 41 to co-operate with the lever springs. Moreover when the comb is in position its barely perceptible lateral movement is limited, leftwardly by the engagement of projections 49 and 50 with the back edges of the slots in lever springs 40 and 44 respectively, and is limited rightwardly by the engagement of the front edges of the same slots with the backs of the depressions above teeth 46 and 41. Tooth 48 prevents the comb becoming disengaged by normal handling of the springset. As before, when the springset and buffer block 5| are mounted on the heelpiece and the armature is in the normal position shown, the upwardly tensioned springs 40 and 43 are carried clear of the buffer block shoulders by the lever springs. Subsequent operation of the armature causes the later springs to be flexed upwardly whereupon the extensions of springs 40 and 43 meet the buifer block while the lever springs 4| through the intermediary of the contacts engages with the so-called fixed spring 42 which is lifted clear of the said block.

It may be mentioned that the comb described with reference to Figs. 4 and 5 is also suitable for use in springsets having but one break, make or changeover contact unit, or two of each type of unit, or one of each type together with one of the other type. For instance, a two changeover springset would employ an additional downwardly tensioned contacted spring mounted above spring 44, the latter being modified to include contacts on both faces. The additional spring would normally rest on the buffer block and would have a long slot so as to clear tooth 48 and projection 50. By way of further example a springset comprising two break units would in the main entail removing spring 42 and inserting a small metal distance piece in the clamped portion, in order to retain the relative positions of the other springs. Should a single contact unit, for instance a changeover, be required, it would preferably be mounted in the lower position, spring 43 would be replaced by a distance piece and the contacted lever spring 44 would be substituted by an additional spring to control the opposite end of the comb.

It follows, in the case of a springset including but one contact unit, that the comb is located by the lever spring of said unit and the addition spring. On the other hand a comb employed in a springset including two or more contact units is located by the lever springs in the lower and upper contact units.

It will be apparent that both of the relays described might well employ two springsets which would be mounted one at each side of the buffer block. Furthermore it may be mentioned that the springset might well form part of a relay or other switching device not having a buffer block or the equivalent.

We claim:

In a switching device having an actuating means, a plurality of elongated substantially stationary spring members and a plurality of elongated operating movable lever spring members stacked with respect to each other, each of said spring members being of generally like length and each having a contact at one end and also having a slot therein between the ends, insulator means for securing one end of each of the stacked spring members in substantially fixed position and approximately uniformly spaced from each other spring member and intermingled with respect to stationary and movable components, an elongated insulating comb having projections along one edge thereof of a number less than the number of spring members and, a smhe ine; e esseshetween them-eje tions said compbeingpositioned to passythrvough the. slot ineach of; said spring membersin suchiman-fl ner that the projections, engage. individual;w movable spring,-members,;en1arged :head and. foot members onsaid comb each having :anedge flushwithalaterak edge of different-slots in. certain ofi said' movable spring members to. interlock the comb; with;-saio1-v certain spring membersgto ire-x tain: the: comb, within the slots 1111'; the :spring. members ..thr0ug-hf-. projections thereof 1 bearingagainetsaid certain spring membersand flexing thesameagainsttheir inherent resiliency, and a contact surface at thevfootof the comb for -en-- gagement with. theaetuating means to lift the 15 comb relativeto the stationary springmembers so that the relationship between the contacted REFERENCES .GITED'Q The following. references are of. record in the file ofiithis' patentzs.

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